Cancer is characterized primarily by an increase in the number of abnormal cells derived from a given normal tissue, invasion of adjacent tissues by these abnormal cells, and spread of malignant cells to regional lymph nodes and to distant sites (metastasis). Clinical data and molecular biologic studies indicate that cancer is a multi-step process that begins with minor pre-neoplastic changes which may under certain conditions progress to neoplasia. Treatment for patients having cancer may include the utilization of drugs, chemotherapy, radiation and in some cases surgery. The particular treatment which is selected is dependent on a number of factors including the condition of the patient and the type of cancer that is to be treated.
Arsenic has been considered to be both poison and a drug for a long time in both Western and Chinese medical practices. In the latter part of the 19th Century, arsenic was used frequently in attempts to treat diseases of the blood in the West. In 1878 it was reported that treatment of a leukemic patient with Fowler's (arsenic) solutions reduced markedly the count of white blood cells. Further interest in the use of Fowler's solution as a palliative agent to treat chronic myelogenous leukemia was reported. Fowler's solution was administered strictly as an oral composition. One of the long recognized effects of exposure to arsenic is skin cancer. The carcinogenicity of arsenic has since been demonstrated by the fact that it can induce chromosomal aberration gene amplification and cellular transformation. Because of the known carcinogenic effect of arsenic, it has not been widely used in humans in Western medicine.
Even with the known carcinogenic effect of arsenic and its toxicity, arsenic has been administered using arsenic trioxide formulations primarily for the treatment of leukemia. Such treatment typically has involved the administration of a plurality of doses of arsenic trioxide over a period of time. For example, U.S. Pat. No. 6,723,351 issued to Warrell, Jr. et al. provides a method of treating acute promyelogenous leukemia by administering 0.15 mg/kg arsenic trioxide once per day for a period of up to five weeks.
U.S. Pat. No. 6,875,451 to Ellison discloses administering arsenic trioxide to a cancer patient having solid tumors daily in amounts from about 10 micrograms to about 200 mgs, and also discloses that such treatment is done with at least one other therapeutic agent such as a chemotherapeutic agent or a radiotherapeutic agent and specifically discloses the administration of arsenic trioxide intravenously in a total daily dose of from 0.5 milligrams to 1.5 mgs. U.S. Pat. No. 6,720,011 to Zhang discloses a method of treating leukemia by administering an aqueous solution of 0.1% to 1% by weight of arsenic trioxide, 0.8% by weight sodium chloride, 10% by weight glucose and water on a daily basis for approximately two to four weeks.
From the above discussion, it is well known that arsenic is both a poison and a carcinogenic agent but that arsenic is still used in treating patients with leukemia and in some instances with solid tumors. It is also clear that there are many different types of cancers, each of which requires a unique treatment protocol that is modified according to the presence of factors predicting for a risk of treatment failure. Thus the development of a broad spectrum anti-cancer agent is extremely desirable.